Exercise training results in depot-specific adaptations to adipose tissue mitochondrial function.

Area of Science:

• Metabolic Health and Exercise Physiology
• Mitochondrial Biology
• Adipose Tissue Metabolism

Background:

• Mitochondrial dysfunction in adipose tissue is linked to insulin resistance and obesity.
• Subcutaneous adipose tissue depots (gluteal and abdominal) exhibit distinct metabolic characteristics.
• Understanding depot-specific mitochondrial adaptations to exercise is crucial for metabolic disease management.

Purpose of the Study:

• To compare mitochondrial function in gluteal (gSAT) and abdominal subcutaneous adipose tissue (aSAT) at baseline and after exercise.
• To examine depot-specific associations between mitochondrial function, body fat distribution, and insulin sensitivity (S_I).
• To investigate the effects of a 12-week exercise intervention on mitochondrial function and metabolic parameters in obese women.

Main Methods:

• Randomized controlled trial involving obese South African women (n=45).
• Intervention group (n=23) underwent 12 weeks of aerobic and resistance training.
• High-resolution respirometry, fluorometry, frequently sampled intravenous glucose tolerance tests, dual-energy X-ray absorptiometry, and MRI were used to assess mitochondrial function, insulin sensitivity, body composition, and ectopic fat.

Main Results:

• Baseline gSAT exhibited higher mitochondrial respiratory capacity and hydrogen peroxide (H₂O₂) production than aSAT.
• Higher gSAT respiration correlated with increased gynoid fat, while higher gSAT H₂O₂ and lower aSAT respiration were linked to reduced insulin sensitivity.
• Exercise training improved insulin sensitivity, reduced gynoid fat and H₂O₂ production, and increased aSAT mitochondrial respiration, correlating with decreased body fat and altered hepatic fat content.

Conclusions:

• Significant depot-specific differences exist in mitochondrial function between gSAT and aSAT, influencing insulin sensitivity and body fat distribution.
• Exercise training induces beneficial adaptations in mitochondrial function across both gSAT and aSAT depots, improving insulin sensitivity.
• Targeting mitochondrial function in specific adipose depots through exercise may be a viable strategy for managing metabolic dysfunction and insulin resistance.